Many schools use a substantial amount of sanitizing and disinfecting products, which are also sometimes used as a general purpose cleaner. The U.S. Environmental Protection Agency (U.S. EPA) and California Department of Pesticide Regulation (CA DPR) registers all “antimicrobial” cleaning products as pesticides. Sanitizers are used to reduce, but not necessarily eliminate, microorganisms from the inanimate environment to levels considered safe as determined by public health codes or regulations. In order for a product to be registered as a sanitizer for inanimate, non-food contact surfaces by the US EPA, it must demonstrate the ability to cause a bacterial reduction of at least 99.9% within 5 minutes.1 Non-food-contact sanitizers are typically formulated to be effective against the types of bacteria typically found in restrooms (such as Salmonella, E. coli and “Staph”), while some also kill a limited number of viruses or other pathogens.

Disinfectants are generally stronger than sanitizers and are, therefore, typically effective against a wider range of bacteria (including, in some cases, antibiotic-resistant strains such as MRSA), viruses (such as flu virus and HIV), and/or fungi (such as Athletes Foot fungus or mildew). Disinfectants are usually used on hard inanimate surfaces and objects to destroy or irreversibly inactivate infectious bacteria, viruses and fungi, but not necessarily their spores.2 Because of the increasing concern about viruses such as H1N1 and the “flu” virus, there is an increasing use of viral disinfectants instead of bacterial sanitizers.

Although all antimicrobial products have risks, there are a few types that appear safer to human health and the environment. These include EPA- and CA DPR-registered disinfectants and sanitizers that contain hydrogen peroxide, citric acid, and thyme oil (thymol) as active ingredients. Like other types of disinfectants and sanitizers, each product should be reviewed for potential health and environmental risks and efficacy (based on dwell time) and other usage instructions.

Since both disinfectants and sanitizers contain chemicals that are designed to kill organisms, it is critical that they be chosen carefully and used properly. Below are our recommendations about best practices relating to the selection, dilution and use of antimicrobial cleaning products, and a directory of disinfectant and sanitizing products that meet our health and safety criteria and are registered for use in California. This directory of products is based on a review of disinfectants and sanitizers that do not contain asthmagens, including ortho-phenylphenol, bleach, quaternary ammonium compounds (quats), or pine oil. This list does not include all antimicrobial surface cleaning products that contain hydrogen peroxide, citric acid, or thyme oil. We excluded those that contain other active ingredients or other “inert” chemicals of concern that are listed on the product’s registration label or material safety data sheet (MSDS). The specific brands are representative; there may be other products with the same or similar formulations that schools want to consider using.

Best Practices for Disinfection

Click on any of these best practices or scroll down to read more details.

Clean first.Since most germs attach to dirt and because dirt rapidly reduces the effectiveness of most disinfectants and sanitizers, surfaces should be thoroughly cleaned before disinfectants or sanitizers are applied – rather than cleaning and either disinfecting or sanitizing simultaneously. If school districts insist on using a one-step cleaning-disinfecting process, they should only use products that are registered as “disinfectant- or sanitizing-cleaners” since their efficacy has been demonstrated to EPA in the presence of 5% organic matter. Determine where and when disinfectants are needed. Some schools use a strong, hospital-grade disinfectant instead of a general purpose cleaner on virtually all surfaces “just in case” it is needed. This unnecessarily exposes custodial workers, students, teachers and other building occupants to these pesticides on a daily basis. It is very important to understand what can be cleaned versus what needs to be sanitized or disinfected. It is best to target disinfectants and sanitizers only in areas that require them. Know the laws and guidelines in your district.

If disinfectants or sanitizers are needed, schools should establish procedures detailing where, when and how they should be used.

* Surfaces that come in direct contact with food (primarily in the kitchen) must be cleaned and then treated with a product that is registered as a food-contact sanitizer, which is registered to kill E. coli and Staph. aureus, and potentially other food-borne pathogens.

* Non-food-contact sanitizers, which reduce pathogens (mostly bacteria) to safe levels, can be used on restroom floors, walls, and toilets on a daily basis.

* Low-level disinfectants are primarily needed to kill bacteria and other pathogens in restrooms, particularly on surfaces that hands can directly touch such as sinks, faucet handles and door knobs. If school districts want to kill viruses or fungi on these “touch points,” they should look for disinfectants specifically registered for use against these organisms since some disinfectants only are formulated to kill bacteria.

* High-level disinfectants, such as those used in hospitals, may be needed in the nurses’ office, if there is an incident resulting in contamination with bodily fluids (such as blood or vomit where the school should follow the OSHA Bloodborne Pathogen Standard). Disinfectants also may be needed in locker rooms and gym areas to kills Athletes Foot Fungus, MRSA (antibiotic-resistant Staph), and other difficult-to-kill pathogens. Schools should have at least one high-level disinfectant on hand for that purpose but generally don’t need to use them regularly.

* While there are often no requirements to do so, some custodial workers and teachers believe that it is important to routinely disinfect desks and other classroom surfaces. The CDC does not include that in any of its guidance about how to combat H1N1 or the flu virus. Teachers who want to use disinfectants in the classroom should do so when students are not present and only if students have coughed or sneezed at their desk. In addition, they should use products that are approved by the school district as “asthma safe.”

* Other surfaces, such as hallway and classroom floors, carpets, walls, mirrors and windows, generally do not need to be treated with disinfectants or sanitizers. These should be cleaned with a general purpose cleaner, neutral floor cleaner, or another cleaner designed specifically for that surface type. Schools should consider using microfiber mops and clothes since they are more effective at removing dirt and germs than conventional string mops and sponges.

* There may be additional disinfection and sanitizing requirements in school facilities that house childcare centers, particularly in diaper changing areas. Special Education classrooms or facilities may also need extra cleaning, sanitizing or disinfection, depending on levels of contamination.

Follow manufacturers’ instructions regarding proper dilution, application and rinsing procedures, and dwell time. Since all disinfectants and sanitizers contain pesticidal ingredients, it is important that they be used properly.

* Schools should use products that are packaged in containers that make it easy to dilute the product accurately – such as automatic dilution equipment – or choose a pre-diluted product. Products with an open spout that allow users to pour the contents directly into mop buckets and spray bottles without automatic dilution equipment can easily result in solutions that are too strong and can expose people to direct contact with the strong chemicals, as well as result in accidental spills of the concentrated product.

* All antimicrobial products must be left on for the required “dwell time” to disinfect properly. Some products must also be rinsed off to prevent exposure to building occupants who may subsequently touch the disinfected surface or to prevent corrosive damage to the floor or other surface if it is left on too long. If disinfectants are wiped or rinsed off before the required dwell time, it is not likely to effectively kill the germs you are trying to eradicate.

* Because disinfectants need to saturate a surface for 1-10 minutes in order to be effective, there is almost no germ-killing benefit from spraying disinfectants or sanitizers into the air. Avoid air fresheners that contain disinfectants or sanitizers because they are often used to mask odors but result in unnecessary exposure to pesticides, are generally not effective at germ-killing, and can cause or aggravate asthma and other health effects.

Carefully Select Antimicrobial ProductsThe U.S. EPA does not allow registered sanitizers and disinfectants to be labeled or marketed as less-toxic or environmentally preferable products, although the Canadian government does allow this. The EPA and several certifying organizations are working to develop standards for safer disinfectants; in the meantime, we are providing information about the pros and cons of various types of disinfecting and sanitizing products that are commonly used by schools. Below is information about the potential health and environmental risks posed by specific types of disinfecting ingredients, as well as generalizations about their efficacy. School districts can determine the product efficacy by reviewing information on the product label as well as registration information on file with the US EPA at http://www.epa.gov/pesticides/pestlabels/.

Since all products used in California need to be approved by the CA DPR, it is also helpful to check its summary of potential health risks and list of pathogens each product is registered to kill according to the State of California (since it sometimes differs from the US EPA’s registration information). This can be found by going to the CA DPR’s Product Label Database and searching by product name, active ingredient, or other parameters at http://www.cdpr.ca.gov/docs/label/labelque.htm.

To enable users to be able to quickly assess the overall potential toxicity level of antimicrobial products, the US EPA requires their labels to carry a signal word. Products that are corrosive or otherwise highly hazardous must carry a signal word of DANGER. Less-hazardous products must have either a WARNING or CAUTION signal word on their label. Relatively benign products are not required to carry any signal words on their label.

When selecting disinfectants, school districts should avoid products containing ortho-phenylphenol and minimize their use of chlorine bleach, quaternary ammonium compounds (“quats”), and pine oil as much as possible because these “active ingredients” are known to cause asthma, severe respiratory effects, and other serious health risks. Instead, look for asthma-safe disinfectants and sanitizers that use hydrogen peroxide, citric acid, and thyme oil to kill bacteria, viruses and other organisms.

Avoid Disinfectants Containing ortho-PhenylphenolTypically found in hospital-grade disinfectants, ortho-Phenyl phenol should be avoided by schools because this active ingredient is a “chemical known to the State of California to cause cancer” and on the Association of Occupational and Environmental Clinic’s (AOEC) list of chemicals that can cause new cases of asthma via respiratory sensitization.Minimize Use of Chlorine Bleach (Sodium hypochlorite) Bleach typically consists of a solution of 5.25-6% sodium hypochlorite in “regular” brands to 6.15% in “ultra” brands, along with a small amount sodium hydroxide (lye), which is a contaminant generated in the manufacturing process. It has been used extensively in schools (and other types of facilities) for decades as a surface disinfectant because it is readily available, relatively inexpensive, and versatile. Bleach is considered hazardous because it is corrosive. EPA has recently approved a stronger warning label for a common bleach product: “DANGER: CORROSIVE. Causes irreversible eye damage and skin burns.”3 When bleach is mixed with acids (like vinegar) or other ingredients in cleaners (like surfactants or fragrances), compounds react and can release chlorine gas. Mixing chlorine bleach and ammonia together produces a toxic chloramine gas that can be fatal. Chlorine that enters wastewater can also contribute to the formation of chlorinated compounds, some of which are probable human carcinogens.

Although sodium hypochlorite is not on the AOEC’s list of “asthmagens,” chlorine gas is listed (as a respiratory sensitizer). Moreover, a study on occupational asthma conducted by four state health departments (including California’s) found 43 cases of “new onset asthma” were attributed to the use of bleach, mostly by custodial workers. Bleach is not only severely irritating to human skin, eyes and lungs, it also corrosive to many surfaces. Using bleach regularly on the floors, for example, can eat away at floor polish, resulting in the need to strip and wax floors more often. This is both costly and hazardous to workers. Another problem with many bleach products is that they are packaged in open containers, which can result in improper dilution – either too strong or too weak.

How effective is chlorine bleach? The efficacy data on sodium hypochlorite is confusing. While the Centers for Disease Control, California’s Childcare Licensing Regulations, and other health authorities recommend mixing ¼ cup of bleach per gallon of water and leaving this solution on surfaces to be disinfected for two minutes, this contradicts the label instructions for broad-spectrum disinfection, which have been approved by US EPA. For example, according to the Clorox website, the following steps must be followed to effectively disinfect using chlorine bleach: Mix ¾ cup of bleach per gallon; pre-wash surface; mop or wipe with bleach solution; allow solution to contact surface for at least five minutes; rinse well and air dry. Chlorine bleach is only effective against viruses, fungi and certain bacteria (such as MRSA) with this higher concentration and longer dwell time. (Leaving a solution of ¼ cup of chlorine bleach per gallon of water on a surface for two minutes only disinfects against bacteria.) In addition, bleach solutions should be mixed daily to work as intended.

Minimize Use of Quaternary Ammonium Compounds (“Quats”) Quaternary ammonium compounds have been linked to asthma and hypersensitivity. Benzalkonium chloride, specifically, and quats, in general, are listed by the AOEC as asthmagens/respiratory sensitizers. According to the US Centers for Disease Control, a few case reports of occupational asthma have been documented as a result of exposure to benzalkonium chloride, a commonly used quat. EPA classifies “quats” as “severe skin and eye irritants.” They are highly toxic to fish and other aquatic species. This toxicity is exacerbated by the fact that quats do not readily degrade; instead they tend to concentrate in sewage sludge when cleaning products are flushed down the drain. Some disinfectants that contain “quats” but have a neutral pH are marketed as environmentally preferable products because they can replace “quats” that are caustic (have an extremely high pH of >12). While these “neutral quats” are an improvement over their caustic predecessors, they still carry serious health risks because quats are respiratory sensitizers that can cause new cases of asthma even when they are present in small amounts.Minimize Use of Pine OilAntimicrobial surface cleaning products that contain pine oil as their only active ingredient are used as disinfectants and non-food-contact sanitizers primarily against bacteria. A few pine oil products that also contain isopropyl alcohol are registered for use against both bacteria and fungi, but not viruses. And other pine oil products that can also kill viruses typically contain quaternary ammonium compounds (“quats”) in addition to pine oil. Currently, there are no pine oil products registered with the EPA that are effective at killing Human HIV-1 virus, Hepatitis B or C, Norovirus, antibiotic-resistant bacteria such as MRSA or VRE, or Mycobacterium tuberculosis (TB). This includes pine oil products that contain other active ingredients.4 In addition, the only pine oil products that are EPA-registered as effective against Influenza A (flu virus) also contain quats.

The typical dwell time for pine oil-based products is 10 minutes. This includes products containing pine oil as the only active ingredient, and products that contain quats as active ingredients in addition to pine oil.

There are many other pine oil-containing cleaning products on the market that are not registered as antimicrobials since pine oil is widely used as a scent. Pine-Sol Original Brand Cleaner is marketed using the tag-line, “The Powerful Scent of Clean” and scented Pine-Sol products are not registered as antimicrobial products in California.

Pine oil is severely irritating to the eyes, moderately irritating to the skin, and may cause skin rashes and other allergic reactions. Although pine oil is not on the AOEC’s list of asthmagens, the European Union has classified it as a dangerous substance “known to cause human aspiration toxicity hazards.” Moreover, pine oil is in the same family of chemicals as rosin and tall oil, which are two other pine-derived chemicals that are listed as respiratory sensitizers by the AOEC, and some pine oil disinfectants also contain tall oil in addition to pine oil.

Although pine oil is not considered a cancer-causing agent, a recent study conducted in a simulated residential setting found that using pine oil-based cleaning products can create secondary pollutants such as formaldehyde, a known human carcinogen, for 12 hours after cleaning a surface.5 There are many documented poisoning incidents involving pine oil-based cleaning products. Pine oil can permeate the skin and may cause central nervous system effects and kidney damage.

Consider Switching to Asthma-Safe Disinfectants and SanitizersAlthough all antimicrobial products have risks, there are a few types that appear safer to human health and the environment. These include EPA- and CA DPR-registered disinfectants and sanitizers that contain hydrogen peroxide, citric acid, and thyme oil (thymol) as active ingredients. Like other types of disinfectants and sanitizers, each product should be reviewed for potential health and environmental risks and efficacy (based on dwell time) and other usage instructions. The downloadable Directory of Asthma-Safe Disinfectants and Sanitizers provides details on several asthma-safe disinfectants and sanitizers. We developed this list of products based on a review of disinfectants and sanitizers that do not contain asthmagens as the “active ingredient,” including ortho-phenylphenol, bleach, quaternary ammonium compounds (quats), or pine oil, as well as screening inert ingredients listed. In addition, the products we listed are registered by both US EPA and CA DPR.

Hydrogen peroxide (H2O2): There is a new generation of asthma-safe sanitizers and disinfectants that contain hydrogen peroxide as well as a stabilized form of hydrogen peroxide called “Accelerated” hydrogen peroxide (AHP). Products containing AHP tend to be effective at killing a broader spectrum of pathogens with a shorter dwell time than products containing a similar amount of unstabilized hydrogen peroxide. The San Francisco Department of Public Health has been testing one AHP-containing product called Oxivir Tb6 in childcare facilities because it has broad spectrum efficacy against bacteria (including MRSA and Tb), viruses and fungi with a short, one-minute dwell time against most organisms (5-10 minutes for Tb and fungi) and does not have to be rinsed off after being applied. In comparison, quats have a 10-minute dwell time against most organisms and must be rinsed off after use.

Another AHP-containing product, which is packaged as a concentrate, is Oxivir Five 16, which at a dilution of 1:16 is effective at killing a broad spectrum of bacteria (including MRSA) and viruses (including flu virus and Hepatitis) with a five-minute dwell time. It has a 10-minute dwell time against fungi and is not registered to kill Tb. Diluted 1:64 with a 10-minute dwell time, it is a bacterial sanitizer with efficacy against HIV. Diluted 1:128 it is a bacterial sanitizer, and diluted 1:256 it is a general purpose restroom cleaner without any antimicrobial claims.

Most antimicrobial products containing unstabilized H2O2 are registered as non-food-contact bacterial sanitizers or low-level disinfectants capable of killing bacteria as well as some viruses; at least one product can also kill fungi (including Athletes Foot Fungus). Some of the CA-registered antimicrobial surface cleaning products that contain unstabilized hydrogen peroxide as their only active ingredient include Envirox’s H2Orange2 Concentrate 117 and 118 (3.95% H2O2), Concentrate 112 (7.95% H2O2) and One (1% ready-to-use). These products are considered disinfectants and have a 5-minute dwell time. None of these products are approved for use against MRSA or Tb. Note: some products marketed as peroxide disinfectants (such as Betco’s Oxyfect-H) contain quaternary ammonium compounds or other antimicrobial compounds. Be sure to check the product label and MSDS before using.

One caution about using products containing H2O2 is that they tend to have a relatively low (acidic) pH, particularly in their concentrated form. While H2O2 is corrosive to the eyes, skin and lungs when it is in a concentrated solution (>5%), in its dilute form it is relatively benign for custodial workers to use as it does not cause asthma. (Most peroxide-containing products have <1% of this active ingredient in their diluted, use solution.) Nevertheless, it is important for users to wear gloves when handling these products and to choose products with automatic dilution systems that prevent exposure to concentrated solutions. Like chlorine bleach, some peroxide-based antimicrobial products can wear away surfaces such as metal and floor polish, especially if used regularly. Therefore, peroxide-based antimicrobial products should be used primarily in restrooms and on other compatible surfaces. Unlike “quats”, hydrogen peroxide is not toxic to aquatic species and it rapidly degrades in the environment into oxygen and water.

Thymol: Thymol is derived from the cooking herb thyme. Although thymol may be severely irritating to the eyes, skin and respiratory system in its pure form, it is not considered an asthmagen and its irritation effects are reported to be much weaker in dilute solutions containing this chemical ingredient (although some users in pilot tests have noted a strong smell associated with these thymol-based cleaning products).

Eight products containing this active ingredient are registered for use in California as broad spectrum disinfectants and sanitizers for non-food-contact surfaces. And because thyme oil is “generally recognized as safe,” by the US Food and Drug Administration (FDA) and EPA has concluded that thymol has minimal potential toxicity and poses minimal risk since it is intentionally added to food7, some thymol-based antimicrobial products may soon be able to be used to sanitize food-contact surfaces.

The eight DPR-registered products contain thymol as their only active ingredient have concentrations of this active ingredient ranging from 0.05% to 0.23% and one also contains citric acid. All of these products are disinfectants capable of killing bacteria, viruses and in at least one case fungi (such as the Athletes Foot Fungus) and Tb. None are registered to kill antibiotic-resistant strains of bacteria such as MRSA and VRE. All have a dwell time of 10 minutes, making some applications impractical – although unlike “quats”, no rinsing is required. It is important to note that some products containing citric acid are not registered as antimicrobial products as citric acid is sometimes added to toilet bowl and restroom cleaners for other reasons.

Citric acid: Twenty-four antimicrobial surface cleaning products registered for use in California list citric acid as their only active ingredient in concentrations ranging from 0.6% to 8%. Citric acid is not listed as an asthmagen/respiratory sensitizer, although, not surprisingly, the MSDSs for most citric acid-based products list an acidic pH between 1 and 4 and report mild to moderate irritation to the eyes, skin and respiratory system. Nevertheless, none are labeled by CA DPR as corrosive, or list corrosive health effects with use according to their MSDSs. (Some of these and other health risks – such as central nervous system effects – associated with citric acid-based products may be due to the presence of other ingredients such as alcohol- and glycol ether-based compounds.)

The efficacies of the CA DPR-registered citric acid-based antimicrobial surface cleaners vary widely among products. Some are only bacterial sanitizers; these tend to be concentrated products that are diluted prior to use. Others are broad-spectrum disinfectants capable of killing bacteria and viruses and, in some cases, fungi such as Athletes Foot Fungus and mildew. Most of citric acid antimicrobial products have a 5-10 minute dwell time, depending on the organism targeted.

Silver ions: As of September 2009, there were at least nine products containing both silver and citric acid as active ingredients registered for use in California.8 According to CA DPR registration labels, they are all ready-to-use products that contain 0.003% silver (ionic or metallic) and 4.84% citric acid.

These products are used as broad spectrum disinfectants and non-food contact sanitizers, and are capable of killing bacteria, viruses and fungi on hard, nonporous surfaces. They are approved for use in hospitals, schools and office buildings as well as other commercial, institutional and residential settings. They are particularly effective at killing bacteria such as “Staph” and Salmonella (with a 1-minute dwell time), and can be useful in the event of a MRSA outbreak, particularly since the residue from this product does not need to be rinsed off and can continue working as a disinfectant for up to 24 hours. Because these RTU solutions are typically packaged in a spray bottle, they may not be cost-effective for disinfecting floors and other large surfaces. However, they may be practical for treating touch-point surfaces such as sinks, faucets and door knobs.

In general, silver has low toxicity to humans, and most silver that is ingested is rapidly excreted. Silver has been used for many years in medicines, dental preparations, and water purification. The primary health endpoint of concern is argyria, a benign yet permanent skin condition that causes patches of blue-gray discoloration. Although silver can cause lung and kidney lesions at high doses, this type of exposure is not anticipated from use of silver-containing disinfecting products. Silver compounds are not skin or eye irritants or sensitizers and are not classified as “asthmagens” (respiratory sensitizers) by the AOEC or other sources. According to US EPA, high dermal doses to silver may cause mild allergic reactions such as rashes, swelling and inflammation to occur.

Silver is not known to have human carcinogenic potential and does not appear to be a mutagen, according to the US EPA Registration report for this pesticidal ingredient. Silver is not listed by the State of California as a developmental or reproductive toxicant, and there are no data indicating that silver causes developmental toxicity.

All of the products containing silver ions and citric acid that are registered for use in California as surface disinfectants have a low acute toxicity, with either a CAUTION signal word or no signal word on their label.9 MSDSs for several of these products warn only that overexposure to the product “may cause slight eye irritation”. This is likely due to the presence of citric acid, which contributes to their very low (acidic) pH – in the range of 1.8-1.9.10

The MSDS for PureGreen24, one of the silver ion/citric acid-based disinfecting products that is registered for use in California, states that it is not a contact sensitizer; and that none of its ingredients are considered hazardous by OSHA, none are hazardous air pollutants or ozone depleters, and none appear on California’s Prop 65 list of carcinogens, reproductive toxins or developmental toxins. Additionally, this product’s MSDS states that it has a low acute toxicity (LD50 >5000 mg/kg for both oral and dermal exposure routes.) It is classified as practically non-irritating for primary eye irritation by EPA.11

Silver salts are very highly toxic to fish and other aquatic organisms. And since silver ions are heavy metals, they are not likely to biodegrade in sewage sludge. (Note: While these products are not likely to contribute significantly to the silver load in waste water, some sewage treatment plants are trying to address elevated silver levels large due to historic discharges of silver from photographic processing facilities.)

Considering Cleaning Devices with Sanitizing and Disinfecting ClaimsBeyond chemical products there are now cleaning devices and equipment that have sanitizing and disinfecting claims, which may not use chemicals at all.

Electrolyzed WaterAn increasing number of “electrolyzed water” technologies have recently been developed that make a range of claims, including giving users the ability to clean, sanitize and/or disinfect surfaces without the use of chemicals other than water. One model, ActiveIon, claims to be an effective sanitizer that can kill 99.9% of bacteria by applying a slight electrical charge to tap water, which creates “an oxygen rich mixture of positive and negative nano-bubbles.” Other more powerful models, which add salt or other chemicals to the mix, create hypochlorous acid (a dilute bleach-like solution) that can disinfect against a broader range of bacteria, viruses and other pathogens. School districts interested in these technologies should ask manufacturers to show them their EPA and CA “pesticide device registrations,” approved labels and efficacy data against specific pathogens.

Steam Cleaning This technology is commonly used for deep cleaning of restrooms, kitchens and other facilities. While some technologies advertise “sanitizing” benefits, there are no steam cleaning systems registered as antimicrobial devices in California.